Mohamed A.M. Osman

Residues of organochlorine and synthetic pyrethroid pesticides in honey, an indicator of ambient environment, a pilot study

Samples of honey were screened to monitor residues of organochlorine and pyrethroid pesticides. The study meant to examine the quality of honey, and to use honey as a bioindicator of environmental contamination. Residue levels were determined by gas chromatography (GC-μECD). Samples had a wide spectrum of organochlorine and synthetic pyrethroids pesticides, with hexachlorobenzene (HCB) as the most frequently detected organochlorine, followed by permethrin, heptachlor epoxide. Only one sample had a concentration of γ-HCH higher than maximum residue limit of honey (0.01 mg kg(-1)). Residues of organochlorines detected, indicate the presence of some fresh supplies, despite the ban imposed on their use. The study confirmed that honey bee and beehive matrices could be used as gauge for monitoring environment contamination. From public health point of view, the observed levels of pesticide residues in honey do not pose a serious health risk to the consumers, but raises questions of the source of organochlorines.

THE IMPACT OF USING LEAFCUTTING BEES (Megachilidae hymenoptera) WITH DIFFERENT FERTILIZATION TREATMENTS ON ALFALFA SEED PRODUCTION

Alfalfa, Medicago sativa (L, 1753), one of the most important forage crops in the world; leafcutting bees which belong to Family Megachilidae are very promising pollinator of Alfalfa is USA and Canada. Different lefacutting natural nests were discovered in Ismailia (east part of Egypt). Artificial polystyrene foam nests were used for bees nesting; it is easy to manage and handle it in alfalfa fields. Different fertilization treatments were carried out for testing their impact on alfalfa seed production in the presence of artificial nests. The seed production depends basically on the pollination of leafcutting bees (tripping mechanism) more than fertilization treatment; we found no significant differences between different fertilization treatments. It is highly recommended to use phosphorus and potassium fertilizers during the blooming season synchronized with leafcutting bees.

Efficiency, intrinsic competition and interspecific host discrimination of Copidosoma desantisi and Trichogramma evanescens, two parasitoids of Phthorimaea operculella

Abstract Trichogramma evanescens West. (Hymenoptera: Trichogrammatidae) and Copidosoma desantisi Annecke & Mynhardt (Hymenoptera: Encyrtidae) are potential parasitoids of the potato tuber moth (PTM), Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) in Egypt. Discrimination of a parasitized host from an unparasitized host would prevent wasting of time, eggs and reduce competition with conspecifics or heterospecifics. Therefore, we evaluated interspecific host discrimination, multiparasitism and intrinsic competition between the two wasp species. In a choice test, females of T. evanescens showed high interspecific host discrimination only when they were offered 2-day-old C. desantisi parasitized and unparasitized PTM eggs. In contrast, C. desantisi showed high host discrimination and preferred unparasitized eggs to PTM eggs harboring 2-h- or 2-day-old T. evanescens’ eggs. We also evaluated the effect of different introduction sequences on the efficacy of the two wasps. Dissection data indicated that the two parasitoids had a negative impact on each other. There was a significant reduction in the total number of deposited eggs as well as total number of parasitized hosts by each parasitoid. Regarding the rearing experiment, the total number of T. evanescens-induced black eggs or C. desantisi formed mummies in combined treatments was significantly lower than in single parasitoid treatments (control). Moreover, C. desantisi was inferior and did not develop from any multiparasitized host regardless of oviposition order. It was suggested that combined release of the two wasps would not elevate rate of parasitism over that of single parasitoid treatments and competition between them would reduce their efficacy.